Piston for internal-combustion engines



I April 1954 A. H. CHAMBERLAIN 2,676,857

PISTON FOR INTERNAL-COMBUSTION ENGINES Filed Nov. 4, 1950 2 Sheets-Sheet l M VENTO@ I Ill]! 44 n 1v 6 wane 6 dame/ aul" 1-75- 7 April 27, 1954 A, H. CHAMBERLAIN 2,676,357

PISTON FOR INTERNAL-COMBUSTION ENGINES Filed Nov. 4, 1950 2 Sheets-Sheet 2 El yn/ran fi l? flow/e54. ammazmnm 32 6 5 7 Rik/w Patented Apr. 27, 1 954 ;;676357 5 Blame, 12 m eonaesrios we yGINEs eAhntiH -Wkm'Q93! 411 15:BPI ZMQLPQQHE, fictoria, Australia *TQQHF 1 T i i Z-, p te #9 Hi -3299 i1 in rn s b i g e an e r .in t natiicy ad though not exclusively to ;pistons.9f trunk ttype hailing split skirts.

It is the customary practiceiin the reconditioning of internal combustion enginesgof auto- Inobiles to vrebore thecylind ersand fitnew pisvention, aims at the elimination of'theabove disi advantage by thelprov ision ofian improved piston hating the ch'aracteristi c of variable dia neters Within predetermined limits to accurately fit ,arcylinder bore, either new or wornpand particularly a Worn bore to take upvjslackltogachieve in effect the reconditioningof' the internal combustionuengines to defer the 'necessitywof rebormg. iwith the above stated .principal .objective in View, there is provided accordingt toijthe invention,,an adju'stable'piston of ;the typeherein specified, comprising fiexibleskirtportions separated by a longitudinally disposed slot and at least one deformable mber bridgingi heslot andiembedded,atueach end in one of the skirt, portions Q said ,member including a .p thereof ofiset inwardly from; alinemfent. withithe skirtrportions, wherebya decrease oran increase ofthe extent of ofisetwillrespectively expand or contract. the flexible -.skirt; portions to. fit la cylinder ,bore. More specifically there is .provide dnbetwee n the flexible skirt portions and eg-tendmgtransversely acrossithe .gap or :split them ablii i li artsgas A m th Split ar embedded n skirt portions, and .which upon appropriate deformation spreads the skirt portions more rwide- 1y apart or contraetsnthe {skirt portions more closely together. The .piston upon the {skirt portions} being thus appropriately adjusted, assumes "a =.diameter ,to fit the bore of the cylinder. Thus inlieu of reboring the cylinders, the iexisting ,pistonsr may be conveniently expanded to fit the cylinders i h a v u sta i andlabour.

The pist n aec rs ir t ibsiinve i' used in engines which have been origin 7 a 43E99 wi h Pere 2 Earring 11 a1 re on n .q tim twin which have beenreconditioned-bye previous re- TiS th .-.reo. ,iz9d.-pra9ti v rebore vcy i tiers Ent rtai -tem ted qmina ve iz ever, cylinders so 'reconditionedare seldoniheld .wple ,limit tit bemeth pra t to s -t cylinder to an approximate oversize v, and then machine the pist on to fit the cylinder. The piston according to the i n-uentionrbeing adjustable yer a reasonably,widerange of sizescan be sold .or distributed finishedto the nominal standard oversize and thenradj ustedby the mechanic installing the piston so as to fit theparticularbore.

Qonv ni n ii tmemamma rran m n the deformable member comprises a lengthfof wire or metal stripiwhicht is disposed within the skirt 9v b siqnian a i an es imf g o x n 1y a ross thelongitudinal split in the araeeathaski fi p rtiqne th-pf vire ormetalstrip for parts of ereo V embedded in the opposite in the processof castingwthe piston.

he length fof wire .orstr-ip may mpleter ing or a substantially comc h is, entir ely,er nbedded in thepist, except at the part. which bridges the i E 5 ,l 'fi a airp ietri si 9 w re ar -u d ate Spaced distance apart to bridge the longitudinal slot, the s trips or wires may. comprise opposite sides 91? 7. 4 ma H me-th o e bn J v ichare embedded inthe-skirt-poriqa h fsas atm' ee At the point at which the wire or strip bridges the longitudinal slot and ,extends between the skirt p ti ns, the former is constructed with a or be nd -which is disposed substantially k. .91 withheQircsm e en f h piston. v

e longitudinal slot or gap .at the pointat li r it @9 t w; ened j to provide ,access of asuitable tool to the lgink oribend.

By s lging or pli$ing uponthe convex side heap x or' royvn of thebendor kink,-the bend or lgin k may be more or less straightened to thereby separate or expand the flexible skirt portions on oppgsitesides of thelongitudinal slot, h ppiicationpfpressureto the concave apex thebendingor'curvatureof the ,or wire maybe increasedto contractor draw pnsm rec p e iq ethe titleh st a' t n n 0f ameter of the piston to fit a worn cylinder, while the increase in curvature of the bend or kink and resultant contraction of the skirt portions will decrease the diameter of an oversize piston to fit a cylinder of somewhat less diameter.

The metal comprising the wire or strip is nonresilient or inelastic and upon deformation the relative straightening or increased curvature of the kink or bend is retained, thereby maintaining the relative expansion or contraction of the skirt portions. Mild steel has been found suitable for the construction of the kinked wire or strip.

The invention will be better understood from the description of the illustrative adjustable trunk piston depicted in the accompanying drawings.

In these drawings:

Fig. 1 is a side elevation of the illustrative piston.

Fig. 2 is a side elevation partly sectional of the piston shown by Fig. l. j

Figs. 3 and 4 are part transverse sections on the lines 3-3 and 4-4 respectively of Fig. 1.

Fig. 5 is a longitudinal section on the line 55 of Fig. 1. r

Fig. 6 is a view in perspective of a part of the illustrative piston shown separately.

Fig. 7 is a view in perspective of a part alternative to the part shown by Fig. 6.

Figs. 8 and 9 are diagrammatical views illustrating the actions of the tool shown by Fig. 8 in expanding and contracting the illustrative piston respectively.

Fig. 10 is a transverse section of a modified adjustable piston.

Referring to these drawings in more detail, the numeral 5 designates generally the illustrative piston having skirt portions 6 and 1 positioned on opposite sides of a longitudinally disposed slot 8 and located between the open or lower end of the piston and a partly circumferential slot 9 in which the slot 8 terminates at the upper end.

The skirt portions 6 and I are relatively thin and flexible, and it will be apparent that responsive to forces applied in directions substantially at right angles to the longitudinally disposed slot 8, the skirt portions 6 and I may be expanded by thrusting forces and contracted by retractive forces.

In order that the skirt portions may be readily expanded or contracted, there are provided strips III of a suitable mild steel bridging the slot 8 and mounted in the skirt portions 6 and I, see particularly Figs. 3 and 4.

The strips II! are located at required distances from the open end of the piston and from the partly circumferential slot 9, and the ends of the strips are embedded or incorporated in the skirt portions 6 and I during the process of casting the piston.

The part of each strip I0 bridging the longitudinally disposed slot 8 is formed with a bent, cranked, offset or curved section II which is centralised relatively to the longitudinal slot, while the portions I2 of the strips on opposite sides of the curved section H are approximately straight.

The metallic strips III may be separate and constructed as shown by Fig. 7, but in order to effect a secure bonding of the strips with the skirt sections 6 and I, the former may comprise opposite sides of a rectangular frame I3, the other opposite sides III of which connect together the opposite strips I0 and areincorporated in the skirt portions -6 and I in" the process of casting.

Referring more particularly to Figs. 3 and 4., it will be apparent that if the curved section I I be straightened, the strip III will be lengthened and resultantly the skirt portions 6 and I will be thrust apart or expanded.

Conversely, if the bending of the curved section II be increased, the strip III will be shortened, and resultantly the skirt portions 6 and 'I will be drawn closer together or retracted.

Accordingly, it will be apparent that the piston 5 may be adjusted to accurately fit an engine cylinder by varying the curvature of the bent section II so as to expand or contract the skirt portions 6 and I as required.

In order to ensure flexibility of the skirt portions 6 and I, stiffening ribs 28 are formed in the interior of the piston 5 at or about the ends of the skirt portions remote from the slot 8, and at these ends the skirt portions are somewhat reduced in thickness.

In the modified construction shown by Fig. 10, the bent section II bridging the slot 8 separating the skirt portions 6 and I, comprises a part of a continuous wire ring 29 which is embedded in the piston in the process of casting, and moreover reinforces the latter.

The deformation of the bent section II in this modified construction to expand or contract the skirt portions 6 and 'I is effected precisely as hereinbefore described.

In order to enable the skirt portions 6 and I of this modified construction to be expanded and contracted the ribs 30 extending around the inner periphery of the piston and encasing the wire ring 29 may be recessed as at 3|.

In accordance with recent or modern practice, the pistons 5 above described, are made of slightly elliptic form or shape, the plane of the minor axis passing through the centre of the gudgeon or wrist pin bosses, and the plane of the major axis being perpendicular to the plane of the minor axis and coincident with the plane of oscillation of the connecting rod. The difference in length between the major and minor axes is of the order of .005 to .008 inch.

Referring again to Fig. 8, the skirt portions 6 and I in expanding will move radially outwards about the zones or areas of flexure lying approximately between the lines A. defining the boundaries of these zones or areas, the expanding movements of the kirt portions being in the directions indicated by the feathered arrows.

Accordingly, it will be appreciated that the expansive movements of the skirt portions 6 and I will increase the ellipticity of the piston in the direction of the major axis, so that by such an adjustment the piston may be increased in size to compensate for wear.

Similarly, the skirt portions in contracting will move radially. inwards about the zones or areas of flexure lying between the lines A as indicated by the feathered arrows in Fig. 9, thus reducing the ellipticity of the piston.

In order to enable a Working tool to engage both sides of the number I I with a view either to increasing the extent of the offset to reduce the peripheral dimensions of the skirt or to decrease the offset with a view to increasing the peripheral dimensions of the skirt, the slot is enlarged as at 32 where windows in the skirt portions are clearly illustrated. Any suitable working tool may therefore engage both sides of the member II to exert therequired deforming action.

I claim:

1. In an adjustable piston having a head portion, Wrist pin bosses and a skirt depending from said head portion and separated into flexible skirt portions by a longitudinally disposed slot, said skirt defining thrust faces for the piston disposed at 90 rotation relatively to the Wrist pin bosses, the provision of first integral stiifening means for each skirt portion extending longitudinally thereof adjacent each boss, second integral stiffening means for the skirt portions extending longitudinally thereof adjacent each side of the slot, a relieved portion for each skirt portion intermediate each first and second stiffening means defining a longitudinal axis of flexure, at least one deformable member bridging the slot and embedded at each end in the second stiffening means, said member including a portion thereof oifset from alinement with the skirt portions, hereby an increase or decrease of the extent of offset will respectively decrease or increase the dimension across the thrust faces of the skirt by causing rotation of the flexible portions thereof about said axis portions Without substantially disturbing the alinement of the Wrist pin bosses, and the slot oeing enlarged at the location of said member to leave a substantial clearance for the engagement of a Working tool with said member from either side to vary the extent of the offset thereof in either direction whereby the flexible skirt portions may be expanded or contracted to fit a cylinder bore.

2. An adjustable piston as claimed in claim 1, having a pair of said deformable members bridging the longitudinally disposed slot in spaced parallel relation.

3. An adjustable piston as claimed in claim 2, wherein the deformable bridging members are of flat bar section.

4. An adjustable piston as claimed in claim 2,

6 wherein the spaced deformable bridging members comprise parts of an open frame having other parts thereof embedded in the flexible t portions on opposite sides of the longi- A tadinally disposed slot.

5. An adjustable piston as claimed in claim 4., wherein the open frame is of rectangular form having a pair of the opposite sides comprising the spaced deformable bridging members, and the other pair of opposite sides embedded respectively in each of the flexible skirt portions.

6. An adjustable piston as claimed in claim 1, wherein the deformable bridging member comprises a section of an annular member having the remainder thereof embedded Within and extended around the piston Wall and coaxial with the circumference of the piston.

7. An adjustable piston as claimed in claim 6, wherein the annular member comprises a ring of Wire having therein a bend or kink comprising the deformable bridging member.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,522,709 Austin Jan. 13, 1925 1,730,120 Jardine Oct. 1, 1929 1,975,974 Reid Oct. 9, 1934 2,093,475 ONeil Sept. 21, 1937 2,114,040 Bechmann Apr. 12, 1938 2,151,071 Beck Mar. 21, 1939 2,221,535 Berry Nov. 12, 1940 2,337,362 Willinger Dec. 21, 1943 2,548,414 Wilson Apr. 10, 1951 FOREIGN PATENTS Number Country Date 412,555 Italy Jan. 5, 1946 

